There is a related printing apparatus capable of high-speed duplex printing. The related printing apparatus adjust the number of the sheets to be conveyed based on the size of the sheets. Thereby, the related printing apparatus selects the most suitable feeding operation based on the size of the sheets. For example, such a related printing apparatus sets a size of sheets to be printed in advance, adjusts the number of sheets to a suitable number based on the sheet size set in advance, and conveys the suitable number of sheets.
However, the printing apparatus of the related art has the following problems. That is to say, in the related art technique, a sheet conveyance is controlled based on the assumption that the sheet size is set in advance and sheets of the set size are set on a feeding section. Since the size of the sheets is set in advance in the related art, it is not possible to convey the sheets in an appropriate manner in a case where a size of sheets actually conveyed is different from the size of sheets set in advance. Examples of such case are that users have made mistakes in sheet settings or that sheets were automatically fed from a different sheet tray in response to detection of absent of sheet.